[Semi-OT]: Dual Head Laptop?

["Gary Hennigan" <glhenni@sandia.gov>]

I've got a buddy that wants to switch to using just a laptop for all
his needs, instead of the laptop/workstation combo he currently
uses. One thing he's decided he doesn't want to do without though is a
dual-headed setup when he's in the office. My initial thought was that
surely someone made a docking station with an AGP slot and he'd just
tell his laptop to use the video card in the DS and disable the
adapter in the laptop. My Dell laptop seems to be able to do the
disable on-board VGA trick. 

Unforunately it doesn't appear to me that AGP is a feature in any of
the big-boys (IBM, Dell, etc.) docking stations. Now my thought is
he'd be stuck with a PCI display card, like the Matrox G450 PCI. In
theory I think that would be fine, but theory and practice often
diverge, especially where linux and laptops and X are concerned. Is
anyone using a setup like this?

I know the G400 AGP works fine in a workstation using X in Xinerama,
which is my current setup, but I'd like to be more confident it'd work
with a G450 PCI in a docking-station application before I recommend.

Thanks,
Gary